Kidney stones, and also naturally-occurring stones in the bladder and the ureter can be exquisitely painful, and often require surgical relief. Excision or destruction of stones in the bladder and sometimes in the ureter can be relatively easily accomplished, but removal of stones from the kidney is a major procedure.
Removal of stones from the kidney is a very serious and traumatic procedure. A large incision is made in the body. The kidney is essentially removed from the body and cut open. The stone or stones are then removed, whereupon the kidney is sutured and returned to the body, with the body then being sutured. Typical recovery time is on the order of six months.
Chemotherapy is available as a non-invasive therapy for uric acid stones. In this therapy the urine is alkalized. The existing stone thus is dissolved over a substantial period of time, and in most cases the patient can be cured before his condition becomes acute. However, the patient's condition is often already acute when the stone is discovered, and immediate surgery is imperative. Attempts at chemical dissolution of other types of stones have not been successful.
There are procedures for removing stones from the bladder which do not require cutting of the body. The first known of these is an invasive procedure in that the necessary device is inserted through the urethra. A correlary approach to ureteral and kidney stone disintegration is known as the percutaneous approach. A needle is inserted through the skin to the renal pelvis, the collecting area of the kidney. The needle is hollow and a guide wire is inserted through the needle into the kidney. The needle is then removed, and successively larger tubes are run in over the guide wire, leaving a fine tube 8 mm in diameter. Viewing and stone cracking apparatus then are inserted through this tube to crack or disintegrate the stone. The approach is still invasive and traumatic to the patient.
In both the percutaneous approach and the insertion through the urethra, an electrohydraulic impulse is provided. A high energy capacitor is discharged establishing a hydrodynamic wave which destroys the concretion upon contact. In either of these approaches the electrode must be in close proximity to the stone, and a cystoscope having an optical telescope is utilized to visualize the spark-generating electrodes.
Ultrasonic waves on the order of 27 KHz are used as an alternative technique to disintegrate bladder stones. An optical device and an ultrasound converter are carried by a hollow steel probe which is inserted through the urethra. High frequency electrical energy is transformed into mechanical energy by an ultrasound converter and carried by a hollow steel probe which must be in contact with the bladder stone.
With both electrohydraulic impulses and ultrasonic disintegration of bladder stones it was initially necessary for the energy source to be very close to or to effect physical contact with the stone. Although this did require invasion of the body, major cutting of the body was not necessary.
One approach has been made to the non-invasive breaking up or disintegration of kidney stones in the body as disclosed in U.S. Pat. Nos. 3,942,531 Hoff et al and 4,311,147 Hausler. The first of these patents is exemplified in a machine commerically available in the Federal Republic of Germany from Dornier System GmbH. A few of the Dornier machines are now in use in the United States. Such machines are quite large since they require the patient to be immersed in a tub of water in a crouched, face-up position. Two dimensional X-ray procedures are utilized to determine the position of the stone by moving the patient. The machine includes an underwater spark gap shock wave generator which lies outside of the patient's body and at the first focus point of an ellipsoidal reflector. The patient is moved around in the water bath by several mechanisms utilizing a two-dimensional X-ray technique until the kidney stone is positioned at the second focal point of the ellipsoid. Since X-rays are used only radio opaque stones can be located. The shock wave is then generated, and passes through the water bath and through the patient's body to convey the energy to the kidney stone. The kidney machine requires a 40 square meter room 3 meters in height. The machine base is 6 meters by 1 meter. The cost of such a machine, which may be expected to rise with inflation, is on the order of 2 million dollars, plus ten percent of the price of the machine each year for a service contract. The service contract includes the cost of the technician who must be on hand at all times when the machine is in operation. It is contraindicated if the ureter is blocked, since the material must pass out through the ureter. It is also unsuccessful with radio transparent or translucent stones, since they cannot be located by X-ray techniques. It must be emphasized that precise aiming of an external shock wave is necessary since energy focused into an air or gas pocket in the body can cause damage to interface tissue.
Efforts have been made to produce a physically smaller machine which does not require immersion of the body of the patient in a tub of water. One patent showing such an effort is Forssmann, U.S. Pat. No. 4,539,989. The structure in this Patent utilizes an ellipsoidal reflector coupled to the body through a liquid-filled cushion and having an energy absorber and reflector on the back side of the body. A three-dimensional X-ray aiming technique again is used.
Efforts have been made to utilize ultrasound techniques for aiming, see for example the co-pending patent application of William R. Shene, Christopher Nowacki, and Alfred G. Brisson, Ser. No. 666,770, filed Oct. 31, 1984 for "KIDNEY STONE DISINTEGRATOR". An earlier effort at ultrasound aiming which was abandoned in favor of X-ray aiming is found in Chaussy, "Extracorporeal Shock Wave Lithotripsy", Beruhrungsfreie Nierensteinzertrummerung durch extrakorporeal erzeugt, fokussierte Strosswellen", Beitrage zur Urologie, vol. 2 (Karger, Basel, 1980), ISBN 3-8055-1901-X Translation Copyright 1982 by S. Karger AG, P. O. BOX, CH-4009 Basel, Switzerland. Printed in Germany by Ernst Kieser GmbH, D-8900 Augsburg ISBN 3-8055-3620-8,128/328 pages 1-112, see especially pages 38 and 39 and FIG. 21. In accordance with the Chaussy disclosure, the ultrasonic transducers were fixed in the structure of the ellipsoidal reflector and operated through the water bath coupling the spark gap to the body containing the kidney stones. It appears that Chaussy abandoned attempts at ultrasonic aiming in favor of X-ray aiming.